1. Field of the Invention
The invention relates to a panel structure of a plasma display panel.
2. Description of the Related Art
Recent years, a plasma display panel of a surface discharge scheme AC type as an oversized and slim display for color screen has been received attention, which is becoming widely available.
FIG. 7 is a schematically plane view of a conventional plasma display panel of a surface discharge scheme AC type. FIG. 8 is a sectional view taken along the V3xe2x80x94V3 line of FIG. 7. FIG. 9 is a sectional view taken along the W4xe2x80x94W4 line of FIG. 7. FIG. 10 is a sectional view taken along the W5xe2x80x94W5 line of FIG. 7.
In FIG. 7 to FIG. 10, on the backside of a front glass substrate 1 to serve as a display screen of the plasma display panel, there is sequentially provided with a plurality of row electrode pairs (Xxe2x80x2, Yxe2x80x2); a dielectric layer 2 overlaying the row electrode pairs (Xxe2x80x2, Yxe2x80x2); and a protective layer 3 made of MgO which overlays a backside of the dielectric layer 2.
The row electrodes Xxe2x80x2 and Yxe2x80x2 respectively consist of wider transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 each of which is formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and narrower bus electrodes Xbxe2x80x2 and Ybxe2x80x2 each of which is formed of a metal film, complementary to conductivity of the transparent electrode.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are arranged opposing each other with a discharge gap gxe2x80x2 in between, and alternate in the column direction to form display lines (row) L on a matrix display screen.
A back glass substrate 4 faces the front glass substrate 1 with a discharge space Sxe2x80x2, filled with a discharge gas, in between. The back glass substrate 4 is provided with a plurality of column electrodes DI arranged to extend in a direction perpendicular to the row electrode pairs Xxe2x80x2 and Yxe2x80x2; band-shaped partition walls 5 each extending between the adjacent column electrodes Dxe2x80x2 in parallel; and a phosphor layer 6 comprised of a red phosphor layer 6(R), green phosphor layer 6(G) and blue phosphor layer 6(B) which individually overlay side faces of the partition walls 5 and the column electrodes Dxe2x80x2.
In each display line L, the column electrodes Dxe2x80x2 and the row electrode pair (Xxe2x80x2, Yxe2x80x2) cross each other and the partition walls divide the discharge space Sxe2x80x2, to form a unit light emitting area, and thus a discharge cells Cxe2x80x2 is defined therein.
In the plasma display panel, as illustrated in FIGS. 8 and 9, on the :backside of the dielectric layer 2 and at a portion opposing to the back-to-back bus electrodes Xbxe2x80x2 and Ybxe2x80x2 extending in parallel to each other, an additional dielectric layer 2A is formed to extend along the bus electrodes Xbxe2x80x2 and Ybxe2x80x2 in parallel.
The additional dielectric layer 2A is formed to protrude from the backside of the dielectric layer 2 toward the inside of the discharge space Sxe2x80x2. The additional dielectric layer 2A has a function of suppressing the spread of a surface discharge d, caused between the opposite transparent electrodes Xaxe2x80x2 and Yaxe2x80x2, toward the respective bus electrodes Xbxe2x80x2 and Ybxe2x80x2 in the discharge space Sxe2x80x2, in order to prevent occurrence of a false discharge between the discharge cells Cxe2x80x2 adjacent to each other in the column direction.
In the above surface discharge scheme AC type plasma display panel, an image is displayed as follows:
First, through address operation, discharge (opposite discharge) is caused selectively between the row electrode pairs (Xxe2x80x2, Yxe2x80x2) and the column electrodes Dxe2x80x2 in the respective discharge cells Cxe2x80x2, to scatter lighted cells (the discharge cell in which wall charge is formed on the dielectric layer 2) and nonlighted cells (the discharge cell in which wall charge is not formed on the dielectric layer 2), over the panel in accordance with the image to be displayed.
After the address operation, in all the display lines L, the discharge sustain pulse is applied alternately to the row electrode pairs (Xxe2x80x2, Yxe2x80x2) inunison. In each lighted cell, for every application of the discharge sustaining pulse, surface discharge is produced in each space between a pair of additional dielectric layers 2A adjoined to each other sandwiching the lighted cell. The surface discharge generates ultraviolet radiation, to excite the red phosphor layer 6(R) and/or the green phosphor layer 6(G) and/or the blue phosphor layer 6(B), formed in the discharge space Sxe2x80x2, for light emission, resulting in forming the display image.
As explained above, the conventional plasma display panel (PDP) is configured such that the additional dielectric layer, 2A which is formed at a position opposing to the bus electrodes Xbxe2x80x2 and Ybxe2x80x2 to extend in the row direction, limit""s the spread of the discharge in the column direction to present interference between the discharges caused in the discharge cells Cxe2x80x2 adjacent to each other in the column direction.
However, as shown in FIG. 10, the conventional PDP has a clearance rxe2x80x2 which is formed between the partition wall 5 and the dielectric layer 2 and between the adjacent discharge cells Cxe2x80x2 in the row direction in order to feed and exhaust a discharge gas into and from the discharge cells Cxe2x80x2. For this reason, as illustrated in FIG. 7, the surface discharge d in one discharge cell may spread via the clearance rxe2x80x2 to an adjacent discharge cell Cxe2x80x2 in the row direction, to possibly cause interfering discharges.
Although the spread of the discharge in the column direction is passably limited by the additional dielectric layer 2A as explained above, if the surface discharge d develops across the additional dielectric layer 2A, it is impossible to completely prevent the interference between the discharges in the adjacent discharge cells Cxe2x80x2 in the column direction.
The possibility of such interference between the discharges in the row direction and the column direction increases, as a pitch between the discharge cells decreases in relation to the high definition of an image. In the event of interfering discharges, lighted and unlighted discharge cells may be reversed producing an instable and inaccurate image.
The present invention has been made to solve the above problems associated with the conventional plasma display panel.
It is therefore an object of the present invention to provide a plasma display panel which is capable of effectively preventing interference between discharge in adjoining discharge cells to display a stable image.
To attain the above object, a plasma display panel according to a first invention includes, a plurality of row electrode pairs extending in a row direction and arranged in a column direction to respectively form display lines, and a dielectric layer overlaying the row electrode pairs on a backside of a front substrate; and a plurality of column electrodes extending in the column direction and arranged in the row direction on a back substrate facing the front substrate with a discharge space in between; and unit light emitting areas formed to be partitioned by a partition wall having at least vertical walls extending in the column direction in a discharge space corresponding to each intersection of the column electrode and the row electrode pair. Such plasma display panel features a first additional dielectric layer protruding from a backside of the dielectric layer toward the inside of the discharge space and extending along an edge of the unit; light emitting area extending parallel to the row direction; and a second additional dielectric layer formed to protrude from a portion of the backside of the dielectric layer opposing the vertical wall of the partition wall toward the inside of the discharge space, and extend in the column direction to shield the adjacent unit light emitting areas in the row direction from each other in cooperation with the vertical wall.
In the plasma display panel according to the first invention, a surface discharge caused in each row electrode pair upon forming an image, is located between the first additional dielectric layers to be limited from spreading into the adjacent unit light emitting area in the column direction. This prevents occurrence of interference between discharge in the adjacent unit light emitting areas in the column direction.
In addition, in the plasma display panel, the second additional dielectric layer formed on the dielectric layer shields the adjacent unit light emitting areas in the row direction in cooperation with the vertical wall of the partition wall. This inhibits the spreading of the surface discharge into an adjacent unit light emitting area located in the row direction, and thus prevent the occurrence of interference between discharge in the adjacent unit light emitting areas in the row direction.
As described above, according to the first invention, the first additional dielectric layer and the second additional dielectric layer effectively prevent the occurrence of interference between the discharges in any unit light emitting areas adjacent to each other in the row direction and the column direction. This therefore allows stable display of the images.
To attain the aforementioned object, a plasma display panel according to a second invention features, in addition to the configuration of the first invention, in that a clearance is formed in the second additional dielectric layer or the vertical wall of the partition wall to communicate between the unit light emitting areas adjacent to each other in the row direction.
According to the plasma display panel of the second invention, since the second additional dielectric layer and the vertical wall of the partition wall limit the spread of the surface discharge into an adjacent unit light emitting area located in the row direction, the occurrence of interference of the discharges is prevented. And also, since the adjacent unit light emitting areas in the row direction communicate with each other through the clearance formed in the second additional dielectric layer or the vertical wall of the partition wall, it is possible to feed and remove the discharge gas into and from the discharge space in each unit light emitting area while preventing the interference between the discharges. In addition, it is also possible to ensure the priming effect of causing the discharge between the adjacent discharge cells in the row direction such as in a chain reaction, namely causing the discharge to transfer to the adjacent discharge cell.
To attain the aforementioned object, a plasma display panel according to a third invention features, in addition to the configuration of the first invention, in that the partition wall has a transverse wall extending in the row direction, and defines the discharge space into a chessboard-square-like pattern with using the vertical walls and transverse walls to form the unit light emitting areas, and in that the first additional dielectric layer and the transverse wall of the partition wall shield the adjacent unit light emitting areas in the column direction from each other.
According to the plasma display panel of the third invention, since the adjacent unit light emitting areas in the column direction are shielded from each other by the first additional dielectric layer and the transverse wall of the partition wall, as compared with the case of shielding by only the first additional dielectric layer, it is possible to completely prevent the spread of the surface discharge into an adjacent unit light emitting area located in the column direction. This further effectively prevents the interference between the discharges, resulting in the stable displaying of images and high definition of images.
A plasma display panel according to a fourth invention features, in addition to the configuration of the first invention, in that a black layer is formed on a face of the vertical wall of the partition wall on a display surface side. This prevents reflection of ambient light incident upon the vertical wall of the partition wall.
A plasma display panel according to a fifth invention features, in addition to the configuration of the third invention, in that a black layer is formed on a face of the transverse wall of the partition wall on a display surface side. This prevents reflection of ambient light incident upon the transverse wall of the partition wall.
A plasma display panel according to a sixth invention features, in addition to the configuration of the first invention, in that a black layer is formed on the first additional dielectric layer. This prevents reflection of ambient light incident toward the transverse wall of the partition wall.
A plasma display panel according to a seventh invention features, in addition to the configuration of the first invention, in that a black layer is formed on the second additional dielectric layer. This prevents reflection of ambient light incident toward the vertical wall of the partition wall.